The present invention relates to a plasma display panel and, more particularly, to an alternating-current, plasma display flat panel having plasma discharge maintaining electrodes of a two-layer structure.
Known as an alternating-current, plasma display flat-panel having discharge maintaining electrodes of a two-layer structure is a display panel reported in the proceedings of IDW ""00, at page 611. As shown in FIG. 1A, for example, the display panel described in the literature has a dielectric layer 130 and a protective layer 134 formed into a laminate on a discharge space 120 side surface of a transparent glass 104 having a display surface side surface 104a. A plurality of pairs of first discharge maintaining electrodes 140 are formed in a stripe manner between the glass substrate 104 and the dielectric layer 130. The first discharge maintaining electrodes 140 are formed by a transparent ITO (Indium Tin Oxide) film or the like.
Second discharge maintaining electrodes 144 formed by a metallic layer of low resistance are buried inside the dielectric layer 130 between the first discharge maintaining electrodes 140 and the protective layer 134 in such a manner as to correspond to the first discharge maintaining electrodes 140. The second discharge maintaining electrodes 144 are connected to their corresponding first discharge maintaining electrodes 140 at an electrode lead portion, so that the second discharge maintaining electrodes 144 are maintained at the same potential as the first discharge maintaining electrodes 140.
The above-mentioned literature reports that such an alternating-current, plasma display, flat panel having discharge maintaining electrodes of a two-layer structure can improve luminous brightness and luminous efficiency as compared with a conventional display panel with no second discharge maintaining electrodes 144.
In addition, as shown in FIG. 1B, a display panel is known which has a structure with discharge maintaining electrodes 140 but without second discharge maintaining electrodes, and it has bus electrodes 142 formed along edges of a pair of discharge maintaining electrodes 140 at sides distant from each other. The bus electrodes 142 are formed by a metallic film of lower electric resistance than that of the discharge maintaining electrodes 140 formed by a transparent conductive film. This is because the high-resistance discharge maintaining electrodes 140 alone have too high a resistance value along a direction of length of the discharge maintaining electrodes, which is disadvantageous to the manufacturing of large-screen displays.
Incidentally, the conventional plasma display panel has the bus electrodes 142 formed along the edges of the pair of discharge maintaining electrodes 140 at the sides distant from each other, rather than the sides adjacent to each other, because such an arrangement has been considered to increase brightness. Since the strongest discharge occurs on the sides adjacent to each other of the pair of discharge maintaining electrodes 140, it has been considered better to dispose the bus electrodes 142 formed by a metallic film having a light shading property away from the portion where the strong discharge occurs.
From a viewpoint of improving the luminous brightness and the luminous efficiency of a flat-panel display, there is a desire to employ discharge maintaining electrodes of a two-layer structure as shown in FIG. 1A. Further, from a viewpoint of reducing the resistance of discharge maintaining electrodes, there is a desire to provide bus electrodes on the discharge maintaining electrodes, as shown in FIG. 1B. However, if the discharge maintaining electrodes of the two-layer structure shown in FIG. 1A are further provided with discharge bus electrodes 142, as shown in FIG. 1B, then there occurs the following problem.
The second discharge maintaining electrodes 144 and the bus electrodes 142, which are each formed by metallic film for a lower resistance value, block display light emitted from the discharge space 120 to the display surface side surface 104a, resulting in a decrease in brightness.
Accordingly, it is an object of the present invention to provide a plasma display panel that can efficiently generate strong vacuum ultraviolet rays by plasma, and that enables relatively low-voltage driving even at a high luminous brightness and luminous efficiency.
In order to achieve the above object, according to an aspect of the present invention, there is provided a plasma display panel including:
a transparent first substrate having a display surface side surface;
a second substrate disposed such that a sealed plasma discharge space is formed between the first substrate and the second substrate;
a first dielectric layer formed on a discharge space side surface of the first substrate opposite from the display surface side surface;
at least one pair of transparent first discharge maintaining electrodes formed in a stripe manner between the first substrate and the first dielectric layer;
a second dielectric layer formed on a discharge space side surface of the first dielectric layer;
at least one pair of second discharge maintaining electrodes formed in a stripe manner between the second dielectric layer and the first dielectric layer so as to correspond to the first discharge maintaining electrodes, the second discharge maintaining electrodes having an electric resistance lower than the electric resistance of the first discharge maintaining electrodes; and
at least one pair of bus electrodes disposed so as to be overlapped by the second discharge maintaining electrodes along a direction of length of two edges adjacent to each other of the pair of first discharge maintaining electrodes as viewed from the display surface side surface of the first substrate, the bus electrodes having an electric resistance lower than the electric resistance of the first discharge maintaining electrodes.
Preferably, the bus electrodes and the second discharge maintaining electrodes completely overlap each other. Alternatively, the bus electrodes and the second discharge maintaining electrodes may overlap each other at least in part.
Preferably, the width of the bus electrodes is smaller than the width of the second discharge maintaining electrodes.
Preferably, the distance between the pair of second discharge maintaining electrodes is smaller than the distance between the pair of bus electrodes.
The distance between the pair of second discharge maintaining electrodes is preferably less than 50 xcexcm and 5 xcexcm or more, more preferably less than 30 xcexcm and 5 xcexcm or more, and most preferably 20 xcexcm to 10 xcexcm.
The thickness of at least one of the first dielectric layer and the second dielectric layer is preferably 20 xcexcm or less and 5 xcexcm or more, more preferably 15 xcexcm or less and 5 xcexcm or more, and most preferably 10 xcexcm to 5 xcexcm. The second dielectric layer, in particular, is preferably thinner than the first dielectric layer.
Preferably, at least one of the first dielectric layer and the second dielectric layer is formed by a thin film including at least one of silicon oxides, silicon nitrides, and metallic oxides (for example, aluminum oxide). The second dielectric layer, in particular, is preferably formed by a thin film including a silicon oxide or a silicon nitride.
Preferably, at least one of the first dielectric layer and the second dielectric layer is formed by a thin film forming process. The second dielectric layer, in particular, is preferably formed by a thin film forming process. The thin film forming process is exemplified by a vacuum deposition process, a sputtering process, a chemical vapor deposition process, an ion plating process and the like, although it is not particularly limited to these examples. Incidentally, the first dielectric layer may be formed by a thick film forming process such as a printing process.
The plasma discharge space is filled with a discharge gas, and the concentration of xenon in the discharge gas is preferably 10% or more by volume and 100% or less by volume, more preferably 20% by volume to 100% by volume, and most preferably 30% by volume to 70% by volume. A neon-xenon gas (mixed gas of neon and xenon) or a helium-xenon gas (mixed gas of helium and xenon), for example, is used as the discharge gas, although the discharge gas is not particularly limited to these examples. The pressure of the discharge gas filled into the plasma discharge space is preferably 50 torr to 600 torr (6.7 kPa to 79.8 kPa), and more preferably 150 torr to 500 torr (20.0 kPa to 66.5 kPa), although it is not particularly limited to these examples.